The present invention relates to a control method for a link arm mechanism which is preferably used as a handling mechanism for shifting a test specimen. Furthermore, the present invention relates to a centrifugal operation system comprising an automatic centrifugal machine and an associated conveyor line. The automatic centrifugal machine employs the link arm mechanism for transporting the test specimen from the conveyor line to a rotor to perform a centrifugal separation.
Unexamined Japanese patent application No. 58-160071 discloses a conventional link arm mechanism comprising a shift member (i.e., a mechanical hand) supported by two sliders shiftable in parallel with each other.
An object of the present invention is to provide a control method for the link arm mechanism.
Another object of the present invention is to provide a centrifugal operation system comprising an automatic centrifugal machine and a conveyor line, which is capable of automatically transporting the test specimen from the conveyor line to a rotor of the automatic centrifugal machine or vice versa.
In order to accomplish this and other related objects, a first aspect of the present invention provides a control method for a link arm mechanism. The link arm mechanism comprises a first guide member and a second guide member disposed in parallel with each other. A first slider is shiftable along the first guide member. A second slider is shiftable along the second guide member. A first arm has the length longer than a clearance between axes of the first guide member and the second guide member. The first arm has one end pivotally supported by the first slider. A second arm has the length longer than the clearance between the axes of the first guide member and the second guide member. The second arm has one end pivotally supported by the second slider. A shift member, supporting a working device, is supported by the other ends of the first and second arms.
The method for controlling this link arm mechanism comprises the step of shifting the shift member along a line normal to the sliding direction of the first and second sliders by controlling the sliding positions of the first and second sliders so as to satisfy the following relationship   Bx  =      x1    -                            L2          2                -                              [                                          L1                ⁢                                  xe2x80x83                                ⁢                sin                ⁢                                  {                                                            cos                                              -                        1                                                              ⁢                                          xe2x80x83                                        ⁢                                          (                                                                        x1                          -                          Ax                                                L1                                            )                                                        }                                            +              d                        ]                    2                    
where xe2x80x9cL1xe2x80x9d represents the length of the first arm, xe2x80x9cL2xe2x80x9d represents the length of the second arm, xe2x80x9cdxe2x80x9d represents the clearance between the arm pivot axes on the first slider and the second slider, xe2x80x9cAxxe2x80x9d represents the position of the first slider in the sliding direction and xe2x80x9cBxxe2x80x9d represents the position of the second slider in the sliding direction, and xe2x80x9cx1xe2x80x9d represents the position of the shift member in the sliding direction.
Preferably, the control step for shifting the shift member comprises a calculating step for obtaining a target speed curve of the first slider and a target speed curve of the second slider based on a target speed curve of the shift member.
Preferably, an angle sensor is provided at least at one of the first and second sliders to detect the shifting position of the shift member based on a detected angle of the angle sensor.
Preferably, the control step for shifting the shift member is performed periodically, and the detection of the shifting position of the shift member is performed at least before or after each shifting operation of the shift member.
A second aspect of the present invention provides a centrifugal operation system comprising an automatic centrifugal machine and an associated conveyor line. The automatic centrifugal machine comprises a handling apparatus for shifting a test specimen from a predetermined position, a rotor equipped with a bucket accommodating the test specimen, a drive motor for rotating the rotor, a chamber surrounding the rotor, and a refrigerator for cooling the chamber. The height of this automatic centrifugal machine is equal to or less than 1,450 mm. The conveyor line is for conveying the test specimen, and the height of this conveyor line is in a range from 750 mm to 850 mm.
Preferably, the refrigerator is disposed under the drive motor. The handling apparatus comprises a guide member disposed along a line normal to a rotational axis of the drive motor, a slider shiftable along the guide member, and an arm having one end pivotally connected to the slider and the other end pivotally connected to a shift member. The shift member is equipped with a manipulator hand for holding the test specimen.
Preferably, the drive motor performs a high-speed rotational operation for rotating the rotor at high speeds to give a centrifugal force to the test specimen and also performs a low-speed rotational operation for determining an angular position of the rotor when the rotor is stopped.
Preferably, the drive motor is a servo motor.
Preferably, the automatic centrifugal machine comprises a controller connected to an external control apparatus via a communication cable to control the operation of the automatic centrifugal machine in accordance with a command sent from the external control apparatus.